DESCRIPTION (provided by investigator): The frequent experience of positive affect is a cornerstone of psychological and physical well-being. To maximize such experiences, people must be able to accurately forecast the affective consequences of future events. Our recent work on affective forecasting has investigated how such predictions are made, uncovered mechanisms that promote inaccuracy, and demonstrated some of the implications of these mechanisms for decision making. The present proposal argues that (a) unexpected and unusual events are particularly capable of evoking affective reactions, (b) people are driven to understand and explain such events so that they can control their reoccurrence, and (c) one consequence of understanding and explaining events is that these events lose their power to evoke affect. This simple conceptualization suggests several avenues for future research, and provides a general unifying theme for our past and proposed work. The current proposal describes 20 studies that explore the ways in which understanding and explaining events modulates affective experience, as well as the ordinary person's ability to predict these effects. Studies on "The Mechanics of Affective Forecasting" represent the next step in our effort to understand exactly how people make forecasts about the impact of future events. Studies on "Tactics of the Psychological Immune System" represent our continuing interest in understanding how people deal with negative events, with special emphasis on automatic processes. Studies on "Paradoxes of Immune Neglect" describe some of the potentially important ways in which the ordinary person's misconceptions about the causes of his or her own hedonic states can impact decision making. Finally, studies on "The Pleasures of Uncertainty" and "Reinvigorating Past Pleasures" deals with people's forecasts and experiences of positive events.